The present invention relates to stand-by (i.e., receiving-after-waiting) systems and, more particularly, to stand-by systems for radio communication systems such as portable telephone systems.
Recent popularization of data communication is making it impossible to attain the end solely with conventional wired communication systems, and radio mobile (or portable) communication media such as cellular telephone, cordless telephone, PHS (Personal Handy phone System) and portable telephone are becoming rapidly spread. In addition, a plurality of different radio communication systems usually coexist in the same place or district.
From the standpoint of the user""s convenience, it is preferable that one portable unit can utilize a plurality of different communication systems. Accordingly, Japanese Patent Laid-Open No. 6-343189, for instance, discloses a mobile communication unit, which has a transmitting/receiving circuit for cellular telephone service and one for cordless telephone service. FIG. 4 is a block diagram showing such a prior art mobile communication unit.
This mobile communication unit comprises a receiving circuit 2 for cordless telephone, a demodulating circuit 3 for cordless telephone, a transmitting circuit 5 for cordless telephone, a modulating circuit 4 for cordless telephone, a receiving circuit 6 for cellular telephone, a demodulating circuit 7 for cellular telephone, a modulating circuit 8 for cellular telephone, a transmitting circuit 9 for cellular telephone, a microprocessor 10, a non-volatile memory 11, a key input unit 12 and a display unit 13.
When this mobile communication unit is in a pertaining cellular telephone system service area, it catches a control channel sent out from a cellular telephone base station, system control data is received via the antenna 1 in the cellular telephone service receiving circuit 6, demodulated in the demodulating circuit 7 and analyzed in the microprocessor 10. Thus, the analyzed result is displayed on the display 13 that it is in a cellular telephone system service area. When the mobile communication unit is moved to a cordless telephone service area, it catches a control channel sent out from the base station of the cordless telephone service system, system control data is received via the antenna 1 in the cordless telephone service receiving circuit 2, demodulated in the demodulating circuit 3 and analyzed in the microprocessor 10. Thus, the result of the analysis is displayed on the display 13. In these cases, the signals obtained by the modulating circuits 8 and 4 are transmitted fro the antenna 1 via the transmitting circuits 9 and 5. The non-volatile memory 11 stores contents of ranking priority selection to meet the user""s will of utilizing inexpensive communication fee systems.
The above prior art mobile communication unit has the following problems. In the first place, concerning the stand-by no consideration is given to the utilization of a plurality of different systems. In addition, when transmitting data, switching, although automatic, is performed to only a single system before use. This means that the unit can always use only a single system even when it is subscribed to a plurality of different systems. Secondly, a set of transmitting and receiving circuits are provided for each system, and this can not be sufficient in view of the cost, current consumption and weight.
An object of the present invention, accordingly, is to provide a stand-by system capable of eliminating or providing improvement over the above problems inherent in the prior art.
According to first aspect of the present invention, there is provided a stand-by system adopted in a portable terminal having a common antenna for transmitting and receiving data to and from a plurality of systems, including a waiting control circuit for providing a mode switching signal to a plurality of systems to render these systems to be in a stand-by state at the same time.
The waiting control circuit provides timing signals each corresponding to each of the plurality of systems. The plurality of systems each have a radio unit and a control unit, these units being common to all the systems. The plurality of systems includes at least a digital cellular phone (PDC) system and a personal handy phone (PHS) system. The waiting control circuit includes a plurality of waiting timer circuits each for generating a waiting timing signal corresponding to each of the plurality of systems, and a flip-flop circuit for receiving the waiting timing signals and providing corresponding mode switching signals. The waiting timer circuits include those providing timing signals in cycles of 720 and 1,200 msec. When a plurality of waiting timing signals are coincident in timing, the system performs the operation until it can receive the data in the next timing.
According to a second aspect of the present invention, there is provided a stand-by system for a plurality of systems including: a radio unit common to the plurality of systems; a control unit common to the plurality of systems; a timing signal generating means for generating a plurality of waiting timing signals for the plurality of systems; and mode selecting means for generating a mode selection signal to select a system function of the plurality of systems in the radio unit and the control unit on the basis of the waiting timing signal from the timing signal generating means.
The mode selecting means is a flip-flop circuit which receives the waiting timing signal and generates the corresponding mode selection signal. The mode selecting means is a flip-flop circuit which receives the waiting timing signal and generates the corresponding mode selection signal. The plurality of systems includes at least a digital cellular phone (PDC) system and a personal handy phone (PHS) system.
According to a third aspect of the present invention, there is provided a stand-by system for a plurality of systems including: a body including a radio unit common to the plurality of systems, a control unit common to the plurality of systems, a timing signal generating means for generating a plurality of waiting timing signals for the plurality of systems; and mode selecting means for generating a mode selection signal to select a system function of the plurality of systems in the radio unit and the control unit on the basis of the waiting timing signal from the timing signal generating means, a receiver and a microphone, and an antenna 26.
When a plurality of waiting timing signals are coincident in timing, the system performs the operation until it can receive the data in the next timing.